The health benefits of garlic

Research supports the ability of this potent bulb to fight bacteria and help us ward off disease.

Garlic is thought to be good for heart health. Photo / Thinkstock

Garlic, the so-called "stinking rose", has probably inspired more folklore and medicinal claims than any other plant in its use over thousands of years.

The ancient Egyptians used it, it's mentioned in the Bible and Talmud and writers down the centuries have extolled its virtues in treating a wide variety of complaints, including parasites, respiratory problems, poor digestion, low energy and insect bites.

In both World Wars it was used as an antiseptic to prevent gangrene. Oh, and it's apparently good for deterring vampires.

Researchers say that a compound in garlic is 100 times more effective than some popular antibiotics at fighting the campylobacter bacterium, one of the most common causes of intestinal illness, and one which is prevalent in New Zealand.

Xiaonan Lu, a researcher at Washington State University, has published results of his work with the garlic-derived compound diallyl sulfide, demonstrating how effective it is in killing bacteria.

The discovery could lead to new treatments for raw and processed meats and food preparation surfaces to prevent campylobacter. New Zealand has one of the world's highest rates of campylobacteriosis. Most infections stem from eating raw or undercooked poultry, or foods that have been cross-contaminated.

Fellow researcher Michael Konkel says: "This is the first step in developing or thinking about new intervention strategies. Campylobacter is the most common bacterial cause of food-borne illness in the United States and probably the world."

Although this research is focusing on external uses, garlic has long has a reputation as an effective anti-microbial substance - one which I tested in the field myself.

When I first travelled in India I contracted some very nasty stomach bugs, resulting in giardia and suspected amoebic dysentery.

The second time I went to India I ate regular doses of raw garlic, swallowing half a clove at a time. In six months I never had a day's illness. Coincidence perhaps? I asked Dr Carolyn Lister, from Plant and Food Research, if garlic is that effective.

She says garlic is definitely known to have antibacterial properties which may be beneficial for health. "It's been used way, way back. Garlic used as an antibacterial has been recognised for a very long time."

She says the key to my use of garlic while travelling was probably that I was taking it raw.

"With quite a lot of compounds they can be negatively impacted by heat. Heating may actually be destroying the compounds which are of benefit. There are some benefits you can still get from cooked garlic, but not all." Crushed garlic in dressings and garlic butter is certainly a more palatable way of taking it than eating raw cloves.

Other properties attributed to garlic are cardiovascular benefits and anti-inflammatory properties which may help ease arthritis. It is also believed to be a protection against some cancers and it helps the body metabolise iron.

Lister has co-authored a paper looking at the beneficial properties of allium species, which includes onions, garlic and shallots. In it she mentions Louis Pasteur's recording of garlic's antibacterial properties as far back as 1858.

Garlic is sometimes referred to as Russian penicillin because, even until quite recently, it was widely used by Russian doctors to treat infections.

"We still don't fully understand the nitty-gritty mechanics of how it works," she says.

Medical researcher Professor Shaun Holt welcomed the new study into garlic, saying it was well worth trying if it could help in the fight against harmful bacteria.

"If it's good at destroying bacteria that's really useful because antibiotic resistance is a big problem. In fact it's one of the top three health issues worldwide. Now natural products are fighting back."

Holt says the medical usefulness of garlic products is well known. "As a medical therapy garlic is associated with the heart. It's very positive and particularly useful for reducing cholesterol levels. As a natural product it has a lot going for it."

Garlic's claims to fame

* Antioxidants help to reduce cardiovascular disease and cancers.

* May help to limit cholesterol, high blood pressure and blood clotting.

* Anti-inflammatory.

* May help to limit loss of brain function, such as Alzheimer's disease and dementia.